Hepatitis B antibody titers in Indonesian adolescents who received the primary hepatitis B vaccine during infancy

Background Hepatitis B (HB) has been classified as moderate-to-highly endemic in Indonesia. HB vaccination, the most effective method to prevent HB viral transmission, induces protective antibodies against HB surface antigen (anti-HBs). However, these antibodies decline in titer over time. Studies on the duration of protection and the prevalence of non-responders in Indonesian adolescents have been limited.Objectives To determine anti-HBs titers in 15-17-year old Indonesian adolescents given primary HB vaccine during infancy and the prevalence of non-responders after a HB vaccine booster dosage.Methods This cross-sectional study was performed from February to September 2008 on adolescents aged 15-17 years in three senior high schools in Jakarta who received complete primary HB vaccines during infancy, based on parents’ recall. Investigations included HB vaccination history, anthropometric measurements, and blood tests for anti-HBs before and 4-6 weeks after a booster dose of HB vaccine.Results Of 94 subjects, 35 had protective anti-HBs and 59 had undetectable anti-HBs. A booster dose was administered to 58 of the non-protected subjects, of which 33 showed anamnestic responses. However, 25 subjects failed to generate protective anti-HBs. Taking into consideration the adolescents with protective anti-HBs before and after the booster dose, serologic protection was demonstrated in 73%. Non-responder prevalence was 27%. The high prevalence of non-responders may indicate bias of parents’ recall.Conclusion Protective anti-HBbs is detected in less than half of Indonesian adolescents given primary HB vaccine during infancy. Following booster dosage, anamnestic responses are noted in one-third of subjects. The prevalence of non-responders is 27%, but confirmation with further study is needed.